1. Field of the Invention
The present invention relates to electric current-producing cells, and more particularly to such cells employing specified cathode-active materials comprising metal-iron-chalcogen compounds and species thereof exhibiting alkali metal incorporation.
2. Prior Art
There has been considerable interest in recent years in developing high energy density batteries for vlotaic cells. Exemplary of the developing systems is a high energy density electrochemical cell utilizing compounds of the transition metal chalcogenides as cathode-active materials and using alkali metal anodes, e.g., as set forth in U.S. Pat. No. 4,009,052. U.S. Pat. No. 3,992,222 describes a cell having, for example, a lithium anode-active material, a molten electrolyte, and mixtures of FeS.sub.2 and various metal sulfides as its cathode-active material. The background section of this patent describes similar systems using FeS.sub.2 cathodes wherein solid phases of Li.sub.2 FeS.sub.2 and Li.sub.4 Fe.sub.2 S.sub.5 may be formed in the cathode during use at high temperatures. U.S. Pat. No. 3,907,589 describes electrochemical cells having alkali metal anodes, e.g. lithium, having molten salt electrolytes, and having cathodes containing mixtures of FeS.sub.2 and Li.sub.2 S. U.S. Pat. No. 4,049,879 describes alkali metal anode, chalcogenide cathode cells wherein the cathode-active chalcogenides are transition metal phosphorus chalcogenides such as Li.sub.4 FePS.sub.3, K.sub.6 FePS.sub.3, Li.sub.3 FePS.sub. 3, LiNaFePS.sub.3, LiNaKFePS.sub.3, LiK(NiFe)PS.sub.3 and the like. Argonne National Laboratory Report No. ANL-76-8 entitled "Proceedings of the Symposium And Workshop On Advanced Battery Research And Design, Mar. 22-24, 1976", pp. A-81 to A-87, teaches the state of the art for high-temperature batteries and describes, for example, the mechanisms involving various alkali metal-Fe-sulfur reactions, intermediate compounds and products in alkali metal/metal sulfide cells, including the formation of such compounds as Li.sub.2 FeS.sub.2 and K.sub.2 Fe.sub.7 S.sub.8 in the cathode.
Notwithstanding the considerable variety of high energy density electrochemical cell systems which have recently been developed, it is believed that the particular cells of the present invention have not been heretofore disclosed or rendered obvious.